[PATCH 0/3] enable new "size" property and runtime pm

[PATCH 0/3] enable new "size" property and runtime pm

[divagar.mohandass]

From: Divagar Mohandass <divagar.mohandass@intel.com>

This series adds support for new "size" property which will be read by the
driver for eeprom size. The existing ACPI has a different default size which
can be overridden with a DSD property value provided by the platform FW.

This series also adds support for runtime PM. The eeprom driver currently
did not have support for runtime PM and the device was kept in D0 throughout.

Divagar Mohandass (3):
  dt-bindings: add "size" property.
  eeprom: at24: add support to fetch device property "size"
  eeprom: at24: enable runtime pm support

 .../devicetree/bindings/eeprom/eeprom.txt          |  2 ++
 drivers/misc/eeprom/at24.c                         | 38 ++++++++++++++++++++++
 2 files changed, 40 insertions(+)

-- 
1.9.1

[PATCH 1/3] dt-bindings: add "size" property.

[divagar.mohandass]

From: Divagar Mohandass <divagar.mohandass@intel.com>

This adds "size" as optional property for i2c eeproms.

"size" should be mentioned in byte and it should refer
to the eeprom size. This will be read by the driver and
used to calculating the number of bytes in read/write calls.

Signed-off-by: Divagar Mohandass <divagar.mohandass@intel.com>
---
 Documentation/devicetree/bindings/eeprom/eeprom.txt | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/eeprom/eeprom.txt b/Documentation/devicetree/bindings/eeprom/eeprom.txt
index 5696eb5..1436569 100644
--- a/Documentation/devicetree/bindings/eeprom/eeprom.txt
+++ b/Documentation/devicetree/bindings/eeprom/eeprom.txt
@@ -32,6 +32,8 @@ Optional properties:
 
   - read-only: this parameterless property disables writes to the eeprom
 
+  - size: total eeprom size in bytes
+
 Example:
 
 eeprom@52 {
-- 
1.9.1

Re: [PATCH 1/3] dt-bindings: add "size" property.

[Rob Herring]

On Thu, Jul 27, 2017 at 10:13:07PM +0530, divagar.mohandass@intel.com wrote:
> From: Divagar Mohandass <divagar.mohandass@intel.com>

Please improve the subject. Add size to what?

> 
> This adds "size" as optional property for i2c eeproms.
> 
> "size" should be mentioned in byte and it should refer
> to the eeprom size. This will be read by the driver and
> used to calculating the number of bytes in read/write calls.
> 
> Signed-off-by: Divagar Mohandass <divagar.mohandass@intel.com>
> ---
>  Documentation/devicetree/bindings/eeprom/eeprom.txt | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/eeprom/eeprom.txt b/Documentation/devicetree/bindings/eeprom/eeprom.txt
> index 5696eb5..1436569 100644
> --- a/Documentation/devicetree/bindings/eeprom/eeprom.txt
> +++ b/Documentation/devicetree/bindings/eeprom/eeprom.txt
> @@ -32,6 +32,8 @@ Optional properties:
>  
>    - read-only: this parameterless property disables writes to the eeprom
>  
> +  - size: total eeprom size in bytes
> +

This should be implied by the compatible string of the eeprom. Why do 
you need this?

Rob

RE: [PATCH 1/3] dt-bindings: add "size" property.

[Mohandass, Divagar]

>-----Original Message-----
>From: Rob Herring [mailto:robh@kernel.org]
>Sent: Friday, August 04, 2017 1:58 AM
>To: Mohandass, Divagar <divagar.mohandass@intel.com>
>Cc: mark.rutland@arm.com; wsa@the-dreams.de;
>devicetree@vger.kernel.org; linux-i2c@vger.kernel.org; linux-
>kernel@vger.kernel.org; Mani, Rajmohan <rajmohan.mani@intel.com>
>Subject: Re: [PATCH 1/3] dt-bindings: add "size" property.
>
>On Thu, Jul 27, 2017 at 10:13:07PM +0530, divagar.mohandass@intel.com
>wrote:
>> From: Divagar Mohandass <divagar.mohandass@intel.com>
>
>Please improve the subject. Add size to what?

I will update the title to say 'add eeprom "size" property' in the next version.

>
>>
>> This adds "size" as optional property for i2c eeproms.
>>
>> "size" should be mentioned in byte and it should refer to the eeprom
>> size. This will be read by the driver and used to calculating the
>> number of bytes in read/write calls.
>>
>> Signed-off-by: Divagar Mohandass <divagar.mohandass@intel.com>
>> ---
>>  Documentation/devicetree/bindings/eeprom/eeprom.txt | 2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/eeprom/eeprom.txt
>> b/Documentation/devicetree/bindings/eeprom/eeprom.txt
>> index 5696eb5..1436569 100644
>> --- a/Documentation/devicetree/bindings/eeprom/eeprom.txt
>> +++ b/Documentation/devicetree/bindings/eeprom/eeprom.txt
>> @@ -32,6 +32,8 @@ Optional properties:
>>
>>    - read-only: this parameterless property disables writes to the
>> eeprom
>>
>> +  - size: total eeprom size in bytes
>> +
>
>This should be implied by the compatible string of the eeprom. Why do you
>need this?

This eeprom "size" property is optional for at24 driver, 
In the at24 driver size information is passed as part of the i2c_device_id' 
driver_data during initial probe. If you want to use an existing ID for an 
eeprom for a different size, there is no way to override it currently. 
By introducing an optional size device property, we can reuse IDs for chips of
different sizes.

This is also consistent with the implementation in the at25 driver.

>
>Rob

Re: [PATCH 1/3] dt-bindings: add "size" property.

[Wolfram Sang]

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> If you want to use an existing ID for an eeprom for a different size,
> there is no way to override it currently. 

Can you give an example for that?


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RE: [PATCH 1/3] dt-bindings: add "size" property.

[Mohandass, Divagar]

>-----Original Message-----
>From: Wolfram Sang [mailto:wsa@the-dreams.de]
>Sent: Monday, September 04, 2017 2:28 PM
>To: Mohandass, Divagar <divagar.mohandass@intel.com>
>Cc: Rob Herring <robh@kernel.org>; mark.rutland@arm.com;
>devicetree@vger.kernel.org; linux-i2c@vger.kernel.org; linux-
>kernel@vger.kernel.org; Mani, Rajmohan <rajmohan.mani@intel.com>
>Subject: Re: [PATCH 1/3] dt-bindings: add "size" property.
>
>
>> If you want to use an existing ID for an eeprom for a different size,
>> there is no way to override it currently.
>
>Can you give an example for that?

There is a CAT24C16/GT24C16S NVMEM chip part of the OV13858
camera module and it is connected to i2c bus on Intel KBL board.
This device will use the existing ACPI ID INT3499 for an eeprom of size 2048 byte.

[PATCH 2/3] eeprom: at24: add support to fetch device property "size"

[divagar.mohandass]

From: Divagar Mohandass <divagar.mohandass@intel.com>

This adds support to fetch device property "size" from _DSD.

There is a CAT24C16/GT24C16S NVMEM chip part of the OV13858
camera module and it is connected to i2c bus on Intel KBL board.
This device will use the existing ACPI ID INT3499 and platform
fw will expose "read-only", "pagesize" and "size" props via _DSD.

Signed-off-by: Divagar Mohandass <divagar.mohandass@intel.com>
---
 drivers/misc/eeprom/at24.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
index 764ff5df..2199c42 100644
--- a/drivers/misc/eeprom/at24.c
+++ b/drivers/misc/eeprom/at24.c
@@ -570,6 +570,10 @@ static void at24_get_pdata(struct device *dev, struct at24_platform_data *chip)
 	if (device_property_present(dev, "read-only"))
 		chip->flags |= AT24_FLAG_READONLY;
 
+	err = device_property_read_u32(dev, "size", &val);
+	if (!err)
+		chip->byte_len = val;
+
 	err = device_property_read_u32(dev, "pagesize", &val);
 	if (!err) {
 		chip->page_size = val;
-- 
1.9.1

[PATCH 3/3] eeprom: at24: enable runtime pm support

[divagar.mohandass]

From: Divagar Mohandass <divagar.mohandass@intel.com>

Currently the device is kept in D0, there is an opportunity
to save power by enabling runtime pm.

Device can be daisy chained from PMIC and we can't rely on I2C core
for auto resume/suspend. Driver will decide when to resume/suspend.

Signed-off-by: Divagar Mohandass <divagar.mohandass@intel.com>
---
 drivers/misc/eeprom/at24.c | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
index 2199c42..0d26681 100644
--- a/drivers/misc/eeprom/at24.c
+++ b/drivers/misc/eeprom/at24.c
@@ -24,6 +24,7 @@
 #include <linux/i2c.h>
 #include <linux/nvmem-provider.h>
 #include <linux/platform_data/at24.h>
+#include <linux/pm_runtime.h>
 
 /*
  * I2C EEPROMs from most vendors are inexpensive and mostly interchangeable.
@@ -501,11 +502,21 @@ static ssize_t at24_eeprom_write_i2c(struct at24_data *at24, const char *buf,
 static int at24_read(void *priv, unsigned int off, void *val, size_t count)
 {
 	struct at24_data *at24 = priv;
+	struct i2c_client *client;
 	char *buf = val;
+	int ret;
 
 	if (unlikely(!count))
 		return count;
 
+	client = at24_translate_offset(at24, &off);
+
+	ret = pm_runtime_get_sync(&client->dev);
+	if (ret < 0) {
+		pm_runtime_put_noidle(&client->dev);
+		return ret;
+	}
+
 	/*
 	 * Read data from chip, protecting against concurrent updates
 	 * from this host, but not from other I2C masters.
@@ -527,17 +538,29 @@ static int at24_read(void *priv, unsigned int off, void *val, size_t count)
 
 	mutex_unlock(&at24->lock);
 
+	pm_runtime_put(&client->dev);
+
 	return 0;
 }
 
 static int at24_write(void *priv, unsigned int off, void *val, size_t count)
 {
 	struct at24_data *at24 = priv;
+	struct i2c_client *client;
 	char *buf = val;
+	int ret;
 
 	if (unlikely(!count))
 		return -EINVAL;
 
+	client = at24_translate_offset(at24, &off);
+
+	ret = pm_runtime_get_sync(&client->dev);
+	if (ret < 0) {
+		pm_runtime_put_noidle(&client->dev);
+		return ret;
+	}
+
 	/*
 	 * Write data to chip, protecting against concurrent updates
 	 * from this host, but not from other I2C masters.
@@ -559,6 +582,8 @@ static int at24_write(void *priv, unsigned int off, void *val, size_t count)
 
 	mutex_unlock(&at24->lock);
 
+	pm_runtime_put(&client->dev);
+
 	return 0;
 }
 
@@ -743,6 +768,13 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
 
 	i2c_set_clientdata(client, at24);
 
+	/* enable runtime pm */
+	err = pm_runtime_set_active(&client->dev);
+	if (err < 0)
+		goto err_clients;
+
+	pm_runtime_enable(&client->dev);
+
 	/*
 	 * Perform a one-byte test read to verify that the
 	 * chip is functional.
@@ -810,6 +842,8 @@ static int at24_remove(struct i2c_client *client)
 	for (i = 1; i < at24->num_addresses; i++)
 		i2c_unregister_device(at24->client[i]);
 
+	pm_runtime_disable(&client->dev);
+
 	return 0;
 }
 
-- 
1.9.1